title: Nanohybrid vs. fine hybrid composite in extended Class II cavities after six years.
abstract: OBJECTIVE
  In a controlled prospective split-mouth study, clinical behavior of two different resin composites in extended Class II cavities was observed over six years.
  
  
  METHODS
  Thirty patients received 68 direct resin composite restorations (Solobond M + Grandio: n=36; Syntac + Tetric Ceram: n=32) by one dentist in a private practice. All restorations were replacement fillings, 35% of cavities revealed no enamel at the bottom of the proximal box, in 48% of cavities remaining proximal enamel width was <0.5mm. Restorations were examined according to modified USPHS criteria at baseline, and after six months, one, two, four, and six years.
  
  
  RESULTS
  Success rate was 100% after six years of clinical service, while the drop out of patients was 0%. Neither materials nor localization of the restoration (upper vs. lower jaw) had a significant influence on clinical outcome in any criterion after six years (p>0.05; Mann-Whitney U-test). Molar restorations performed worse regarding marginal integrity (4 years), filling integrity (6, 12, 24, 48 months), and tooth integrity (4 and 6 years). Irrespective of the resin composite used, significant changes over time were found for all criteria recorded (Friedman test; p<0.05). Marginal quality revealed a major portion of overhangs having been clearly reduced after the one year recall (baseline: 44%; 6 months: 65%; 1 year: 47%; 2 years: 6%; 4 years: 4%; and 6 years: 3%). Beyond the 1 year recall, negative step formations significantly increased due to wear (p<0.05), having been more pronounced in molars (87% bravo after 4 years) than in premolars (51% bravo after 4 years). Tooth integrity significantly deteriorated due to enamel cracks, which increased over time (p<0.05). Enamel chippings and cracks were significantly more frequent in molars (26% bravo after 4 years to 35% after six years) than in premolars (9% bravo after 4 years, 11% after six years). Restoration integrity over time mainly suffered surface roughness and wear (28% after one year, 75% after two years, 84% after four years, 91% after six years).
  
  
  CONCLUSIONS
  Both materials performed satisfactorily over the 6-year observation period. Due to the extension of the restorations, wear was clearly visible after six years of clinical service with 91% bravo ratings.
authors.affiliation: Department of Pediatric Dentistry, Medical Center for Dentistry, University Medical Center Giessen and Marburg, Campus Giessen, Schlangenzahl 14, D-35392 Giessen, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Krämer
authors.forename: Franklin
authors.initials: F
authors.lastname: García-Godoy
authors.forename: Christian
authors.initials: C
authors.lastname: Reinelt
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Feilzer
authors.forename: Roland
authors.initials: R
authors.lastname: Frankenberger
mesh_terms: D000328:Adult; D001641:Bicuspid / Q000293:injuries / Q000473:pathology; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000145:classification*; D003743:Dental Enamel / Q000293:injuries / Q000473:pathology; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D019232:Dental Restoration Failure; D019554:Dental Restoration Wear / Q000145:classification; D003793:Dental Restoration, Permanent / Q000145:classification*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D008963:Molar / Q000293:injuries / Q000473:pathology; D053761:Nanocomposites / Q000737:chemistry*; D011446:Prospective Studies; D019279:Resin Cements / Q000737:chemistry; D019233:Retreatment; D013499:Surface Properties; D014082:Tooth Fractures / Q000473:pathology; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C509998:Grandio; D019279:Resin Cements; C425825:Solobond M; C078484:Syntac dentine adhesive; C121818:Tetric ceram